Practice point

There are currently no specific high-risk gene variants that are associated with mental health disorders that are useful for predictive testings in clinical practice.1,2

Some companies that offer personal genomic testing may include variants that are associated with increased risk of certain mental health conditions. The results are unlikely to have any clinical utility.

What do I need to know?

The causes of mental health conditions, such as schizophrenia, bipolar disorder and depression, are multifactorial, and include environmental, social and genetic factors.
Table 1 outlines the empirical risk according to family history for schizophrenia and bipolar disorder.

Table 1. Empirical risk of schizophrenia according to family history3,4

Risk (%)

Affected relative

Schizophrenia

Bipolar disorder

No close relative (general population risk)

1

2–3

Sibling

9

13

Parent

13

15

Sibling and one parent

15

20

Both parents

40

50

Second-degree relative

3

5

Monozygotic twin

40

70

Dizygotic twin

10

20

Genetic testing

While some genetic variants have been shown to be associated with mental health conditions, there is no genetic test that can predict mental illness with certainty.
Some commercial genetic tests available are used to tailor drug treatments to individuals with a mental health disorder (Pharmacogenomics: Summary). There are currently no Australian clinical guidelines to support such use.1,5

When should I refer?

There is no indication to refer patients with a family history of mental illness (eg couples considering pregnancy) to genetics services.

International Society of Psychiatric Genetics. Genetic testing and psychiatric disorders: A statement from the International Society of Psychiatric Genetics. Brentwood, TN: ISPG, 2017. Available at https://ispg.net/genetic-testing-statement [Accessed 20 December 2017].